CHAPTER 4 DIGESTION & ENZYMES Digestion is the breaking down of food.

CHAPTER 4 DIGESTION & ENZYMES The functions of the main parts of the digestive system or alimentary canal are as follows: The mouth carries out physical digestion (using teeth) and chemical digestion (using the enzyme amylase). The oesophagus moves food to the stomach by waves of muscular action. The stomach has acid which softens food and kills bacteria. Enzymes in the stomach break down food. The stomach churns food to cause physical digestion.

CHAPTER 4 DIGESTION & ENZYMES The liver makes bile which breaks down fats. The pancreas makes enzymes which digest food. The first part of the small intestine completes the breakdown of food. The second part of the small intestine allows the food to be absorbed from the intestine into the bloodstream. The large intestine takes water back into the bloodstream. The rectum stores faeces.

CHAPTER 4 DIGESTION & ENZYMES The functions of the four types of teeth are as follows: Incisors cut and slice food. Canines grip and tear food. Premolars chew, crush and grind food. Molars also chew, crush

CHAPTER 4 DIGESTION & ENZYMES Enzymes are proteins which speed up chemical reactions without the enzymes being used up. The substance produced by an enzyme is called the product. The substance the enzyme acts on is called the substrate. The enzyme amylase acts on starch to produce a reducing sugar called maltose. (HL)

CHAPTER 4 DIGESTION & ENZYMES To investigate the action of amylase on starch: If saliva (amylase) is added to a starch solution, the solution will turn red/yellow when iodine is later added. If saliva is not added to a starch solution, the solution will turn blue-black when iodine is later added.